1. Field of the Invention
The present invention relates generally to an apparatus and method for managing a network device. More particularly, the present invention relates to a network management apparatus and method for managing a communication device using Simple Network Management Protocol (SNMP).
2. Description of the Related Art
Integrated network management is difficult because of the rapid growth of networks in several past years and the advent of various heterogeneous systems. As networks scale up, network device management is becoming essential in many fields.
Therefore, network managers need a network framework for comprehensive management in various network environments. Due to this need, the main standards organization for the Internet, i.e., Internet Engineering Task Force (IETF), has adopted Simple Network Management Protocol (SNMP) corresponding to a relatively simple protocol as a standard for managing a network device based on the Internet.
In a conventional SNMP system, a management system is referred to as a manager and a management target is referred to as an agent. A management information transmission network for connecting the manager to the agent is based on Transmission Control Protocol/Internet Protocol (TCP/IP), and communication using SNMP uses a command for retrieving management information, a command for successively retrieving management information, a command for changing and writing management information, and a command for reporting an exceptional operation on the basis of a management information base (MIB) between the manager and the agent.
The SNMP agent is a software module placed in a management target device and has information about the MIB. This information is delivered to the SNMP manager using SNMP.
Specific information, resources, and so forth, that are to be managed using SNMP are referred to as objects. A collection of the objects is referred to as the MIB. The format of the MIB is defined as part of the SNMP, and the objects are defined using Abstract Syntax Notation One (ASN. 1).
The SNMP agent manages an MIB configured by parameters relating to a network device function. The SNMP manager obtains a specific value from MIBs provided by SNMP agents, and identifies a device state or changes the value.
As described above, an operation for conventionally managing a network using SNMP denotes an operation for obtaining a specific value from MIBs provided by management target devices, identifying a device state, and changing the value.
According to SNMP, a management method can be easily used, and various types of devices using TCP/IP can be developed. Through various Requests For Comments (RFCs), a management range can be easily designated or extended and protocols can be configured simply. Among the many management protocols, SNMP is widely used because it can be easily implemented.
FIG. 1 illustrates a conventional structure and control operation between an SNMP manager 100 and an SNMP agent 102.
First, commands transmitted/received between the SNMP manager 100 and the SNMP agent 102 as illustrated in FIG. 1 will be described.                GetRequest: denotes a request signal for reading an object value;        GetNextRequest: denotes a request signal for reading the next object value subsequent to the current object value;        GetResponse: denotes a response signal to a request;        SetRequest: denotes a signal for writing an object value; and        Trap: denotes a signal for reporting an exceptional situation.        
The SNMP manager 100 and the SNMP agent 102 of FIG. 1 can communicate with each other using the above-described messages.
A conventional development method and a conventional method for interfacing with an application program will now be described with reference to FIGS. 2 and 3.
FIG. 2 is a flowchart illustrating a conventional method for developing the SNMP agent 102.
In step 200 of FIG. 2, a network manager defines an MIB to develop the SNMP agent 102, and defines a structure used for an interface with an associated application program.
In step 202, an MIB file is generated on the basis of the MIB defined in step 200. In step 204, the network manager codes and compiles the generated MIB file, thereby generating the SNMP agent 102.
In step 206, the network manager determines if the MIB or interface has been corrected. If the MIB or interface has been corrected, the network manager proceeds to step 208 to define management items.
In step 210, the network manager generates an MIB file on the basis of the management items defined in step 208. In step 212, the network manager recodes and recompiles the SNMP agent 102 on the basis of the generated MIB file.
FIG. 3 illustrates a conventional interface method between the manager 100 and application programs 304.
In order for the manager 100 to interface with the application programs 304, the agent 102 must know structure and destination information. When a conventional tool for developing the SNMP agent 102 is used, objects 302 corresponding to the management items must be implemented using a structure used in the application programs 304.
In the conventional method for developing the SNMP agent 102, an MIB is designed such that characteristics of a device can be reflected. Content of the designed MIB determines a development range of the SNMP agent 102, a role of the application programs 304 for performing a management function within the device, an interface method between the SNMP agent 102 and the application programs 304, and so on.
A conventional tool is used to effectively develop the SNMP protocol. The development of the SNMP agent 102 using the tool is facilitated when the SNMP agent 102 has necessary data. However, the development of the SNMP agent 102 is difficult and complex because MIB objects have different structures when an MIB object value is obtained through an interface with the application programs 304.
The SNMP manager 100 accesses management items managed in the different application programs 304 within a device through the SNMP agent 102. These management items are expressed by the MIB and differ according to device characteristics. This MIB cannot be perfectly defined at the time of initial development.
Because the SNMP agent 102 is conventionally developed on the basis of the above-described MIB, different SNMP agents 102 must be developed for devices. Items to be managed in an identical device can be frequently changed, added, or deleted. When a change is made, the SNMP agent 102 needs to be corrected.
Since the SNMP agent 102 must be corrected and recompiled whenever the MIB is changed, added, or deleted in the above-described environment, a great deal of time and effort is required for the development.
Accordingly, a need exists for an effective and efficient system and method for managing a communication device using Simple Network Management Protocol (SNMP).